Dynamic force microscopy with atomic resolution at low temperatures

In this paper, we review some of the most important results obtained with our low-temperature force microscope operated in ultrahigh vacuum. In particular, we stress the resolution capabilities on the atomic scale. After describing some recent modifications of our earlier published setup, we first compare quasi-atomic resolution in the contact mode with true-atomic resolution in the non-contact mode on graphite. On xenon, we demonstrate that weak Van der Waals interactions are sufficient to achieve atomic resolution. Thereafter, atomic scale contrast with ferromagnetic tips on nickel oxide, an insulating antiferromagnet, is discussed with respect to recent theoretical calculations regarding the detection of exchange forces. Finally, tip-induced relaxation is visualized by imaging a point defect on indium arsenide at different tip-sample distances. (C) 2002 Elsevier Science B.V. All rights reserved.